Amperage and MAH how is it doubled ?

[lincpimp]

Originally Posted by BrianG

I can see bursts of 1250w. Around 250w is much more common for average power draws in truggies/MT. After all, 1250w on a 6s 5Ah battery will only get you about 5 minutes of runtime...

I got 1250 (more like 1500) bursts in a buggy, but average draw for that was around 30 amps.

[SpeedAssault]

Originally Posted by lincpimp

If you think you need 1250 watts of power to the wheels and you plan to use a motor that is 85% efficient then you will need some thing like 1500 watts of battery power

1250/.85 = 1470

Now the problem iswhere did you get the 1250 from? Someone told you that? Doing the math will get you the numbers, but there are no hard and fast rules on what numbers apply to what vehicle due to the giant amount of variables.

Best to list your setup and intended use and we will do our best to suggest alternatives for lipo power.

I did a search and read that the CC 2200 is 1250 watts and yields 85% efficient.
I dont know the math. But I did just learn the math to get watts from battery.

My setup (pic Below and in my sig)- in middle up drivetrain upgrade so dont look to close, the front is done though.
Custom 4wd 1/5 car (9.lbs no battery), Losi 43/13 ring pinion with a losi 2.0 CD but locked with a 45s/16p, locked rear, 5" tall 1/5 scale FG street slicks and working on a way to swap wheels out for very mild dirt 3.3 tires (4.5-5") for hard pack rally driving, but mostly street stunt, bash drifting , CC Mamba Monster /2200
want 45-55mph and 20 minute minimum runtime

Originally Posted by BrianG

I can see bursts of 1250w. Around 250w is much more common for average power draws in truggies/MT. After all, 1250w on a 6s 5Ah battery will only get you about 5 minutes of runtime...

that is hard to believe/understand that 5000 6s only run 5min.
I have been trying this car out with my mamba max, Thunder P 3s 2250 30c with a Feigao xl 2383 and it drives for 15 minutes until speed of 28mph starts dropping. that was with a Emaxx tranny locked in 2nd and 1/8 street slicks

Originally Posted by lincpimp

I got 1250 (more like 1500) bursts in a buggy, but average draw for that was around 30 amps.

what are you referencing ? dont follow you where u coming from ?

Really really appreciate everyones help, keeps me from going crazy

[Patrick]

Originally Posted by SpeedAssault

that is hard to believe/understand that 5000 6s only run 5min.

Brian's saying that at 1250w CONSTANT a 6s 5000 mah would only last about 5 mins. He meant that it is not a realistic amount of power to use constantly, only in bursts, that's why he said 250w is a more common average power draw in truggys. Which would equal about 25 minutes max runtime from 6s 5000mah (111 watt hours total). Don't know exactly how your car will compare for power usage.

What voltage do you intend to run that car on? If you want run 6s on that motor you'll have to use a smaller pinion than 16t or you'll be geared for over 65 mph.

Don't concentrate too much on the motors 1250w rating, it doesn't mean much for real use. It doesn't mean you'll use 1250w constant, it doesn't mean you'll never use more than 1250w, it just means the motor is rated to handle 1250w. How much power you really use will depend on many factors, but basically the more load you put on it the more power it will use.

[BrianG]

Originally Posted by SpeedAssault

... that is hard to believe/understand that 5000 6s only run 5min.
I have been trying this car out with my mamba max, Thunder P 3s 2250 30c with a Feigao xl 2383 and it drives for 15 minutes until speed of 28mph starts dropping. that was with a Emaxx tranny locked in 2nd and 1/8 street slicks...

Yup, Patrick is right, that's what I meant. If you are running for 15 minutes on 3s 2250mAh cells, this is what your setup is doing:

- Average amp draw is 9A.
- Your estimated burst amp draw is around 65A.
- Your average power is 100w
- Your estimated burst power is around 700w.

The figures make sense given the weight and gearing of your setup. If you geared up and/or made the setup heavier, your amp draw would increase and runtime would decrease.

[RC-Monster Mike]

Just a little more info on "c" ratings:
"c" rating describes the batteries discharge ability in relation to its "capacity". c = Capacity.
a 30c 1500mah battery can only deliver half the power of a 30c 3000mah battery.
1500mah = 1.5ah. So 30c x 1.5 = 45amp discharge ability
3000mah = 3ah. so 30c x 3 = 90amp discharge ability

The given battery's "c"rating never changes, but the discharge ability double when wiring in parallel. So:
2 x 1500mah(wired in parallel) = 3000mah
3000mah = 3ah. so 30c x 3 = 90 amp discharge ability

Wired in series, the discharge ability "as expressed in amp draw" would be 45 amps no matter how many cells are wired in series.

Total "power" is a little different. This is where voltage comes into play and series vs. parallel starts to make more sense. Voltage times amperage = wattage. Wattage is simply an expression of power or energy.

2 x 1500mah 30c Lipo cells wired in series = 7.4volts x 45 amps = 333 watts(power)
Total "capacity" in this example is still 1.5 amp/hours or 1500mah. The voltage doubled with the series connection

2 x 1500mag 30c lipo cells wired in parallel = 3.7volts x 90 amps = 333 watts(power)
Total "capacity" in this example doubled with the parallel conection. the voltage remains 3.7 when wired this way.

In the 2 examples, you can see that you need more than just the cell's "c" rating to determine power - you need the cell's capacity and voltage.

[SpeedAssault]

[[[ First I would like to Say that all you guys are really nice to give your time and help on this and it is greatly appreciated.

? ? ?My SETUP. please tell me what you recommend from your experience and if you could tell me how to do the math.
Custom 4wd 1/5 car (9.lbs no battery), Losi 43/13 ring pinion with a losi 2.0 CD but locked with a 45s/16p, locked rear, 5" tall 1/5 scale FG street slicks and working on a way to swap wheels out for very mild dirt 3.3 tires (4.5-5") for hard pack rally driving, but mostly street stunt, bash drifting , CC Mamba Monster /2200
want 45-55mph and 20 minute minimum runtime ? ? ?

[Quote reply]
oh ok, I get it, it was about being a constant draw.

I'm not sure whether to go with a 2s and 3s in series or just Two 3s in series.
But I like the idea of split weight.

I was shopping for Batt, one site site listed it's C rating and the other site only listed is constant amperage of 75, at the time I did not know how to calculate to see if they were the same and also one battery was a EP and the other did not say and I was going to put them in parallel, by the time I got the answer the 2nd batt was also a EP he told me I should run a NP .So this battery shopping has been a Long confusing deal.

Here;s the lipo's I was looking at :
NeuEnergy 5S-1P 2500
NEU2500EP 5S1P V1 -->http://www.neumotors.com/Site/Battery_Info.html
But I have read and heard that its best to run in series
So it's either a 2s and 3s in series or Two 3s in series